In recent years, there have been proposed and developed various automatic transmissions in which a dog clutch, serving as a meshing mechanism, is used to lock a rotary member to a transmission housing so as to hold the rotary member stationary. One such dog-clutch equipped automatic transmission has been disclosed in Japanese Patent Provisional Publication No. 6-323377 (hereinafter is referred to as “JP6-323377”). However, JP6-323377 does not refer to the difficulty of controlling the timing of operation of such a dog clutch. Actually, the dog-clutch equipped transmission requires an electronically-controlled actuator for engagement and disengagement of the dog clutch, and also requires control data needed to electronically control the engagement/disengagement timing of the dog clutch. Thus, room for simplification of control data is left.